Rotary drainage screen



Dec. 29, 1953 A. T. HURTER 2,664,204

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Patented Dec. 29,l 1953 ROTARY DRAINAGEISGREEN* Alfred T. l Hurter, v MontreaLf, Quebec, Guiada; use

signor to Stadler, Hutter. &1Cnmp,auy, Mntreah.

Quebec, YCanada.

ApplicatiomJune-B, 1950, Serial No. 166325 1' Claim. (El. 2104-199) The present inventionv relates to water`V vextrairtion apparatus and more particularly to-apparatus of this nature utilizedlfor theremoving; of excess waterfrom wood waste, such as bark or the like.

In the usual process of debarkingpulpfwood logs the logs are placed in large tumbler drums that are provided with internal projections adapted to loosen the bark as the logs arewhirled about. ThisA operation is `generally` carried out With water supplied to the drum so as to-keep the logs Wet and aid in the loosening of the bark. As will be understood, the barkrbecomessoaked or impregnated with water and at the Sametime picks up quite a lot of excess moisture externally due to its rough outer surface. The peeledbark is usually sluiced with water from thefbarking drum and dumped into a convenient river or stream, or alternatively piled and allowed to dry after which it is burnt. the disposal of this wood waste presents a considerable problem to the pulp producing industry as in many places there are anti-pollution laws which now forbid the dumping of wood Waste into rivers or streams.

Where such laws exist, the only other practical means of disposing of the bark isto burni-t. As there are great quantities of this material dumped each day from the average mill the process of extracting the excess-water from the bark must be accelerated. If it is just dumpedinfpiles and left -to dry outrnaturally, it will be understood that this takes considerable time and consequently a great deal. of. storage/spacciare quired.

Therefore, the bark is usually rst subjectede'to a preliminary oper-ation which allows theexcess or surface moistureto drain from the-barkr and it is -then placed in bark presses where suflicientA of thel water is vremoved'to allow for etiicientdisposal bycombustion. Without this preliminary step of dewatering,v the bark press would.y soon clog up and further the amount of water .remaining inthe bark would be in excess of the-50 ton 60% moisture content whichv is themaximum possible to' maintain proper disposal by meansof combustion.

Various apparatus has been designed for this excess water removal, for example, inclined scraper conveyors are sometimes utilized; butin orderl to handle the required volume ofi wood waste these are generally lar'geand cumbersome, involvingV complicated. systems of. conveyors, chains, and gearsv which necessarily requires -con siderable initial outlay' for' their installation and also subsequent high maintenance costs.

At the present time The present invention recognizes` theseV dif 'culties 2 and5 aims; to provide' ausatisfactorfysolution` by providing anladditional perforated drum or screen-intowhich f thefbark can be discharged from:the tumbler drum and rotated so as to -drain away most oithis excess'water.`

The present apparatus is designedY so as t0 require.a.minimum of f maintenance for its eilicient operation andfurther requires considerably lessv space forv itsr installation asl compared with prior art apparatus usedfor this purpose.

The apparatus isf notl intended to force the waterl from theA interior of. the bark but merely to agitata the. bark while allowing the surplus 'Water to be drained off from the exterior of the bark.

Accordingly; the invention is a bark draining ory revolving` screen that comprises essentially of a perforated drum that is. mounted so as tobe rotatable? about a horizontal axis and whichy includes internal d-eflecting members' that are adaptedtoa'gitate and carry the bark at a retarded.speedf-.along the' length of the drum.

More specificallia. a preferred construction of a barkrevolvingscreen constructed in accordance with the invention` comprises of a perforated cylindrical, drumfthatvisl provided atl each end withannular riding rings that are supported for rotationf, on spaced apar-t trunnion wheels. The front-end oft-hev drum is closed o-ii by a casting which includesa. centrally located inlet opening andthe rear endcf the drum is constructed so as to provide an unrestrictedA dischargeoutlet equal totheuinternaldiameter of therdrum.. A plurality. of.` defiecting, members are mounted withinthe drum inlregular spaced apart sequence to frmaspiral formation about a major portion of the longitudinal. axis of thev drum with the outerV ends ofthedeecting members overlapped crcumferentially. WithV this arrangement, the rotation o'f'thed'rum causes the deflecting memberstoagitate andeuide thewet bark along, the length of. tlieLdrum.whilexthesurplus waterdrains off'througlitheperforations .in the walls of the drum` In'. the; preferred. construction. the rear setr of trunnion wheels are groovedv so as to retain the rear ridingringianddrum from lateral movement. The drum" is provided with an annular driving 'sprocket'that surrounds-thefront endofjthe drum and which. is'preferablyv constructedlin .several' in terl'o'cking 'segments' thatarey secured' to the: pe riplierallmargin. ofi the casting:J formingv the inlet end-fof tli'ev drum.. The main cylindrical body of th'e drum is vreinforced longitudinally 4by radially spaced apart beam members that extend between and are secured to the front casting and a second annular casting that surrounds the discharge end of the drum and serves as a supporting base for the rear riding ring.

Having thus generally described the nature of the invention particular reference will be made to the accompanying drawings, and in which:

Figure 1 is a side elevation of a preferred construction of a bark revolving screen according to the invention.

Figure 2 is a diagrammatic view, partially in section, of the construction of Figure 1 to illustrate the action of the revolving cylinder in operation.

Figure 3 is an end view of the inlet end of the construction shown in Figure 1 with the supporting foundation for the inlet spout removed for clarity.

Figure 4 is an enlarged detail view of one of the sprocket sections.

Figure 5 is an enlarged sectional view of Figure 3 along the line 5-5.

Figure 6 is an enlarged horizontal cross section of the construction shown in Figure l to illustrate in more detail the 'assembly'and relative positions of the various portions of the apparatus.

Figure rI is a sectional view of Figure l along the line 1 -1.

Figure 8 is an enlarged detail view of a portion 0f the discharge end of the cylinder, to illustrate more clearly the attachment of the end. casting and longitudinal support members.

Figure 9 is a sectional view of Figure 6 along the line 9 9 to illustrate in more detail the attachment of the deflectors to the interior of the perforated cylinder.

With particular reference to Figures 1, 2, and 3 of the drawings which illustrate in detail and in section a preferred construction of a bark revolving or draining screen as it appears in side elevation, I0 designates the main cylindrical screen or drum of the apparatus. The main drum body IE) is made up of a series of perfrated 'curved plates I2 that are interconnected radially by attachment of their longitudinal marginal edges to the lower flanges of a plurality of radially spaced apart I- beams, I4, preferably by riveting. The I-beams I4 are arranged so as to extend substantially the length of the drum body I0 on the outer peripheral surface and are connected between a casting 20 surrounding the inlet end of the drum and a further annular casting 24 surrounding the discharge end of the drum. The casting 2D includes an outstanding annular flange I8 and the casting 24 an outstanding flange 22 and the ends of the I- beams I4 are secured to these respective flanges.

The casting 20Hsurrounding the inlet end of the drum I0 is formed so as to have a centrally disposed inlet opening 26 surrounded by an outwardly sloping annular flange 21 that extends from the main body of the casting. The outer peripheral edge of the casting 20 isformed so as to extend inwardly and overlap the en ds of the perforated plates I2 and terminate in the outwardly extending annular flange I8to which the beams I4 are detail in Figure 5,` the openings 401inrthe sprocket segments 34 `through which ythe bolts 38fpass'are elongated, andthe segments 3'4 can be adjusted secured and which also serves-as a baseforthe radially by means of a plurality of set screws 42 which are threadably engaged in the upper flange of each segment 34 and are adapted to bear against the upper surface of the casting flange I 8. In the preferred construction illustrated there are three set screws 42 to each segment 34 and these are spaced apart circumferentially so as to allow each segment to be capable of individual adjustment. The upper peripheral surface of the flange I8 of the casting 2D is recessed as indicated at 2I and the front riding ring 30 fits over this recess adjacent to and in front of the driving sprocket 32.

The flange 22 of the annular casting 24 which surrounds the discharge end of the drum I0 includes a flat outer peripheral surface on which the rear riding ring 43 is mounted. The annular casting 24 is positioned on the discharge end of the drum I0 so as to overlap the outer ends of the perforated plates I2 with a portion of the casting 24 protruding beyond the outer marginal edge of the plates I2 so as to provide a means of attaching an annular flanged collar 5I that surrounds the discharge end of the drum I0 with the inner surface flush with the interior of the drum.

"ihe I-beams I4 are secured to the outstanding flanges I8, 22 of the castings 20, 24 by means of angle brackets 44 which are riveted to each side of each end of the beams I4 between the upper end and lower flanges with the other leg of the angle being secured to the castings 20, 24 by suitable bolts 46 and nuts 48.

A plurality of deflecting plates 50 are mounted within the interior of the drum I0 in regular spaced apart staggered sequence so that they follow a spiral conformation about the longitudinal axis of the drum. Each of the plates 50 have the lower side shaped to conform to the internal curvature of the drum II) with the upper side extending straight across so as to effectively block off a segment of the drums inner peripheral surface. The plates 50 are each mounted within the drum at an oblique angle relative to the drum ends so that each plate deflects the bark from the inlet end of the drum towards the discharge outlet and they are arranged relative to the circumference of the drum so that the ends of the plates overlap circumferentially.

As is shown in detail in Figures 6 and 9, the plates 50 are each of sufficient length to obliquely span one of the perforated plates I2 and they are secured to the drum by means of angle plates 52. The angle plates 52 are riveted to the plates 50 and secured along the juncture of each of the perforated plates I2 to the I-beams I4 by means of studs 56 that are inserted through suitable holes drilled between the plates into the lower flange of the I-beams I4 where they are secured by welding. The lower ends of the studs 56 projecting within the drum I0 are threaded and the plates 52 include suitable openings through which the studs 56 pass allowing the angle plates 52 to be fastened in position by means or' suitable nuts and washers 58.

'Ihe riding rings 30, 43 are supported for rotation between spaced apart trunnion wheels 60, 62 journalled in bearing supports 64, B6 fastened to a suitable foundation B. l The rear trunnion wheels 62 are flanged so as to retain the rear riding ring 43 and the drum assembly against lateral displacement. Both sets of trunnion wheel bearing supports are reinforced against spreading by transverse rods 68 that extend across beneath the V' drum I0 adjacent the front and rear..

With particular reference to Figure 3, the driving sprocket 32 is driven by means of a sprocket chain 'l0 from a suitable transmission box C powered through motor D. It will be understood that this driving means is illustrative only and that other suitable driving means could be employed to rotate a revolving screen constructed in accordance with the invention.

In use, the apparatus is preferably erected on a suitable foundation adjacent to the usual barking mills and an inlet spout E mounted on a rigid base F is adapted to deliver bark and Water into the inlet opening 26 of the drum I9, see Figure 2. The drum I is rotated at a speed suflicient to thoroughly agitate the bark as it is moved through the drum I0 by the deiiector plates 50 but not suiiiciently fast to expel any of the water by centrifugal force. The main purpose of the present deflecting plate arrangement is to cause the bark to move along the perforated surface of the drum at a retarded speed to allow the surface water to drain therefrom and is not intended to squeeze or force water from the bark as would be done in a bark press.

The removal of the surface water from the bark has been found to greatly expedite the drying out of the usual piles of wood waste so that their disposal, generally by combustion, can be accomplished with a considerable saving of time.

I claim:

An apparatus for the draining of excess water from water soaked bark comprising a cylindrical drum having an elongated main body, means supporting said drum exteriorly for rotation about an horizontal axis, said drum body consisting of a plurality of elongated perforated plates of arcuate cross section interconnected along the longitudinal marginal edges by attachment to a plurality of longitudinally extending reinforcing beams disposed in equal radially spaced apart relationship about the exterior of said drum body, said drum having an unrestricted discharge outlet equal to the internal diameter of said drum disposed at one end and a centrally disposed unrestricted inlet opening of considerably lesser di- 6 ameter at the other end, a plurality of deector members mounted within said drum in regular spaced apart relationship and in a helical formation extending about a major portion of the longitudinal axis of said drum with the ends of the delector members overlapping circumferentially, each of said deflecting members having a lower marginal edge shaped to conform with the internal curvature of said drum with the upper marginal edge being straight so that each member is adapted to effectively block olf a semicircular segment of said drums inner peripheral surface and means to rotate said drum comprising a sprocket gear surrounding the inlet end of said drum, a sprocket chain, motor means to drive said sprocket chain, said sprocket gear consisting of a plurality of separate arcuate toothed segments each carrying a plurality of teeth and being mounted in equally spaced apart relationship about said drum end and means whereby each of said sprocket gear segments are adjustable radially.

ALFRED T. HURTER.

References Cited in the le vof this patent UNITED STATES PATENTS Number Name Date 390,558 Brock et al. Oct. 2. 1888 577,323` Ross Feb. 16, 1897 673,425 Duncan et al. May 7, 1901 962,168 Scholl Y June 21, 1910 1,169,986 Y Middaugh Feb. 1, 1916 1,279,949 Waterman Sept. 24, 1918 1,424,327 Trout Aug. 1, 1922 1,685,084 Hoyt Sept. 25, 1928 1,831,642 Witham Nov. 10, 1931 2,228,185 Thompson Jan. 7, 1941 2,314,969 Briggs Mar. 30, 1943 2,530,916 Stratton Nov. 21, 1950 FOREIGN PATENTS Number Country Date 252,141 Germany Oct. 14, 1948 

